The functionalization of carbon dioxide (CO₂) as a C1 building block has attracted enormous attention. Carboxylation reactions, in particular, are of major interest for applications in isotope labeling. Due to the inexpensive nature of CO₂, information about its stoichiometric use is generally unavailable in the literature. Because of the rarity and limited availability of CO₂ isotopomers, this parameter is of concern for applications in carbon-isotope labeling. We investigated the effects of the stoichiometry of labeled CO₂ on carbon isotope exchange of phenyl­acetic acids. Both thermal and photocatalytic procedures were studied, providing insight into product outcome and isotope incorporation. Preliminary results on isotope-dilution effects of carbonate bases in photocatalytic carboxylation reactions have also been obtained.

二氧化碳 (CO ₂ ) 作为 C1 构件的功能化引起了极大的关注。特别是羧化反应在同位素标记中的应用非常重要。由于 CO ₂的廉价性质，文献中通常无法获得关于其化学计量用途的信息。由于 CO ₂同位素异构体的稀有性和有限的可用性，该参数在碳同位素标记中的应用受到关注。我们研究了标记 CO ₂的化学计量的影响苯乙酸的碳同位素交换。研究了热催化和光催化程序，提供了对产品结果和同位素掺入的深入了解。碳酸盐碱在光催化羧化反应中同位素稀释作用的初步结果也已获得。